Exploring A Cosmic-Ray Origin of the Multi-wavelength Emission in M31

A recent detection of spatially extended gamma-ray emission in the central region of the Andromeda galaxy (M31) has led to several possible explanations being put forth, including dark matter annihilation and millisecond pulsars. Another possibility is that the emission in M31 can be accounted for with a purely astrophysical cosmic-ray (CR) scenario. This scenario would lead to a rich multi-wavelength emission that can, in turn, be used to test it. Relativistic cosmic-ray electrons (CRe) in magnetic fields produce radio emission through synchrotron radiation, while X-rays and gamma rays are produced through inverse Compton scattering. Additionally, collisions of primary cosmic-ray protons (CRp) in the interstellar medium produce charged and neutral pions that then decay into secondary CRe (detectable through radiative processes) and gamma-rays. Here, we explore the viability of a CR origin for multi-wavelength emission in M31, taking into consideration three scenarios: a CR scenario dominated by primary CRe, one dominated by CRp and the resulting secondary CRe and gamma rays from neutral pion decay, and a final case in which both of these components exist simultaneously. We find that the multi-component model is the most promising, and is able to fit the multi-wavelength spectrum for a variety of astrophysical parameters consistent with previous studies of M31 and of cosmic-ray physics. However, the CR power injection implied by our models exceeds the estimated CR power injection from typical astrophysical cosmic-ray sources such as supernovae.Comment: Accepted to Phys Rev D, 15 Pages, 9 figures, 4 tables, updated figures/tables, added discussio

Tesla Solar Roof

The roof tiles are actually made of textured glass. From most viewing angles, they look just like ordinary shingles, but they allow light to pass through from above onto a standard flat solar cell. These roofs should far outlast the standard 20-year life cycle common for roofing materials used today and are able to power a strandard home.https://openscholarship.wustl.edu/bcs/1237/thumbnail.jp

Multiwavelength Analysis of Dark Matter Annihilation and RX-DMFIT

Dark matter (DM) particles are predicted by several well motivated models to yield Standard Model particles through self-annihilation that can potentially be detected by astrophysical observations. In particular, the production of charged particles from DM annihilation in astrophysical systems that contain magnetic fields yields radio emission through synchrotron radiation and X-ray emission through inverse Compton scattering of ambient photons. We introduce RX-DMFIT, a tool used for calculating the expected secondary emission from DM annihilation. RX-DMFIT includes a wide range of customizable astrophysical and particle parameters and incorporates important astrophysics including the diffusion of charged particles, relevant radiative energy losses, and magnetic field modelling. We demonstrate the use and versatility of RX-DMFIT by analyzing the potential radio and X-ray signals for a variety of DM particle models and astrophysical environments including galaxy clusters, dwarf spheroidal galaxies and normal galaxies. We then apply RX-DMFIT to a concrete example using Segue I radio data to place constraints for a range of assumed DM annihilation channels. For WIMP models with $M_{\chi} \leq 100$ GeV and assuming weak diffusion, we find that the the leptonic $\mu^+\mu^-$ and $\tau^+\tau^-$ final states provide the strongest constraints, placing limits on the DM particle cross-section well below the thermal relic cross-section, while even for the $b\bar{b}$ channel we find limits close to the thermal relic cross-section. Our analysis shows that radio emission provides a highly competitive avenue for dark matter searches.Comment: 21 pages, 9 figures, 2 tables, corrections to figures, additional text, accepted to JCA

The use of recombinant DNA technology in producing pharmaceuticals

Rekombinantna DNA tehnologija podrazumijeva metode kojima možemo prenijeti gene iz jednog organizma u drugi. Time se omogućava dobivanje proteina u organizmima u kojima se ti proteini prirodno ne stvaraju. Takva tehnologija danas ima brojne primjene, a jedna od njih je proizvodnja lijekova. Prvi ljudski protein dobiven iz bakterije E. coli bio je inzulin, 1982. godine. Danas se za manipulaciju gena u svrhu dobivanja rekombinantnih proteina, osim bakterija, koriste i kvasci, životinje, biljke te stanične kulture. Svaka metoda proizvodnje ima svoje prednosti i nedostatke. Glavni nedostatak bakterijama je nemogućnost glikozilacije proteina. Kvasci, kao eukarioti, uspješniji su u tom procesu. Transgenične životinje mogu izlučivati znatne količine proteina u krv, mlijeko, bjelanjak ili urin. Mogu proizvoditi proteine složenih struktura koji moraju proći proces posttranslacijske modifikacije da bi postali aktivni. Upotreba transgeničnih životinja postavlja brojna etička pitanja te pitanja vezana uz sigurnost pripreme takvih proteina. Transgenične biljke mogu proizvoditi velike količine proteina te stvarati proteine kompleksnih struktura. Također takva je proizvodnja jeftina i nema gotovo nikakvih etičkih problema. Najveći nedostatak genetički modificiranih organizama je interakcija s okolišem. Unatoč tome što još uvijek malo znamo o tome kakav bi učinak transgenični organizmi mogli imati na svoj okoliš, možemo reći da je rekombinantna DNA tehnologija u proizvodnji lijekova svojevrsno čudo 20.-og stoljeća.Recombinant DNA technology encompasses various techniques by which we can transfer genes from one organism to another. This way we accomplished production of proteins in organisms for which these proteins are not natural. Such technology has many applications today. One of them is the use in producing pharmaceuticals. Proteins play an important role in the pharmaceutical industry. The first human protein produced in Escherichia coli was insulin, in 1982. Today, we use biotechnology in order to obtain recombinant proteins from bacteria, yeasts, animals, plants and cell cultures. Each manufacturing method has its advantages and disadvantages. The major drawback of bacteria is that they are unable to perform the posttranslation modifications such as glycosylation. Yeasts, as eukaryotes, have some advantages over bacteria in this process. Transgenic animals can secrete significant amounts of protein in blood, milk, egg white or urine. They can also produce proteins with complex structure that must undergo a process of posttranslational modifications. The use of transgenic animals faces many ethical issues and issues of environmental impact of such animals. Transgenic plants can produce large amounts of protein and they can also form complex protein structures. This system of production is cheap and avoids some ethical issues. The biggest disadvantage is interaction with the environment. Although we still know little about how transgenic organisms could affect the nature one day, we can say that the recombinant DNA technology in the production of pharmaceuticals is sort of a miracle of the 20th century

Synchrotron Emission from Dark Matter Annihilation: Predictions for Constraints from Non-detections of Galaxy Clusters with New Radio Surveys

The annihilation of dark matter particles is expected to yield a broad radiation spectrum via the production of Standard Model particles in astrophysical environments. In particular, electrons and positrons from dark matter annihilation produce synchrotron radiation in the presence of magnetic fields. Galaxy clusters are the most massive collapsed structures in the universe, and are known to host $\sim\mu$G-scale magnetic fields. They are therefore ideal targets to search for, or to constrain the synchrotron signal from dark matter annihilation. In this work we use the expected sensitivities of several planned surveys from the next generation of radio telescopes to predict the constraints on dark matter annihilation models which will be achieved in the case of non-detections of diffuse radio emission from galaxy clusters. Specifically, we consider the Tier 1 survey planned for the Low Frequency Array (LOFAR) at 120 MHz, the EMU survey planned for the Australian Square Kilometre Array Pathfinder (ASKAP) at 1.4 GHz, and planned surveys for APERTIF at 1.4 GHz. We find that, for massive clusters and dark matter masses $\lesssim 100$ GeV, the predicted limits on the annihilation cross section would rule out vanilla thermal relic models for even the shallow LOFAR Tier 1, ASKAP, and APERTIF surveys.Comment: accepted to ApJ; removal of LOFAR Tier 2 limits; other minor text changes; conclusions largely unchange